Reduced registration bonding template

ABSTRACT

A dental template for positioning an object on teeth of a patient and method for fabricating the same. The method includes creating a digital model of the patient&#39;s teeth, creating a simplified template model based on the digital model, and fabricating the dental template based on the simplified template model. The template model is simplified by removing certain features of the patient&#39;s tooth anatomy. The dental template can be located on a patient&#39;s teeth using four or fewer positioning teeth.

CROSS-REFERENCE

This application is a continuation application of U.S. application Ser.No. 13/846,322, filed Mar. 18, 2013, now U.S. Pat. No. 9,744,002, issuedAug. 29, 2017, which is a divisional application of U.S. applicationSer. No. 12/338,307, filed Dec. 18, 2008, now U.S. Pat. No. 8,401,686,issued Mar. 19, 2013, the entirety of each are incorporated herein byreference.

BACKGROUND

The present invention relates generally to the field of orthodontics,and more particularly to an apparatus for bonding an orthodontic bracketto a tooth and a method for making the same.

The fundamental objectives in orthodontics are to move a patient's teethto a position where the mechanical function of the dentition isoptimized and to improve the aesthetic appearance of the patient'steeth. The traditional method that orthodontists use is to attachbrackets and wires onto the patient's dentition. Once mounted on theteeth, the wires exert continual light forces through the brackets ontothe teeth. These forces initiate the body's biological bone remodelingresponse and the teeth gradually progress toward their desired finalpositions. During the treatment period, the treatment professionalreactively adjusts the wires and bands to provide a new force and movethe teeth toward their desired or final destination.

Orthodontic brackets are often bonded directly to the patient's teethusing a small quantity of adhesive placed on the base of each bracketand the bracket is then placed on a selected tooth while the patient isin the dental chair. Once the adhesive has hardened, the bracket isbonded to the tooth with sufficient strength to withstand subsequentorthodontic forces as treatment progresses. One shortcoming with thistechnique is the difficulty in accessing the optimal position on thetooth surface for bracket placement on severely crowded teeth or inteeth where the bonding surface is obstructed by teeth in the opposingarch during jaw closure. With posterior teeth, the treatmentprofessional may have difficulty seeing the precise position of thebracket relative to the tooth surface due to limited working space.Also, for most bonding agents, it is necessary to minimize moisturecontamination from the patient's saliva for adequate bonding strength.This can prolong the procedure and also unduly impair the accuracy ofplacement of the brackets on the teeth.

One way to overcome some of the limitations of direct bracket placementis with indirect bonding. Typically, a routine impression of each of thepatient's upper and lower dental arches is taken and either sent to alab or used in the office to create a replica plaster model of eachimpression after the patient has left the office. Brackets are bonded tothe sealed plaster models using a temporary adhesive. A transfer tray isthen made by placing matrix material, usually consisting of siliconerubber, over both the model and brackets. The matrix material thenassumes a configuration that matches the shape of the replica teeth ofthe plaster model with the brackets in the desired position. The matrixmaterial then polymerizes and hardens to form a tray. The temporaryadhesive is removed, and permanent adhesive is placed on the base ofeach bracket in the tray, which is then placed over matching portions ofthe patient's dental arches. Since the configuration of the interiorsurface of the tray closely matches the respective portions of thepatient's dental arches, each bracket location is transferred onto thepatient's teeth at precisely the same location that corresponds to theprevious location of the same bracket on the plaster model. The adhesiveis hardened and the matrix removed, leaving the brackets in the desiredpositions. This indirect method, however, is labor intensive andfabrication of the intricate details (corresponding to the details ofthe patient's teeth) of the tray is complex and time-consuming.

SUMMARY

In accordance with one embodiment, a method is provided for fabricatinga dental template configured to position an object on teeth of apatient. A digital model of the patient's teeth is created. A templatemodel is then created. The template model includes teeth based on thedigital model. Some teeth on the template model include a substantiallyplanar occlusal portion. A dental template is then fabricated using thetemplate model.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary process for fabricating a dental template forpositioning an orthodontic object on a patient's tooth.

FIG. 2A shows an exemplary process for placing an orthodontic object ona patient's tooth.

FIG. 2B shows another process for placing an orthodontic object on apatient's tooth.

FIG. 3A illustrates an exemplary process for fabricating the dentaltemplate

FIG. 3B shows a process for providing four possible templates.

FIG. 3C illustrates an embodiment of a simplified template having onlycertain reproduced features of a patient's teeth.

FIG. 3D shows in greater detail the area in circle A of FIG. 3C.

FIG. 3E shows in greater detail the area in circle B of FIG. 3C.

DESCRIPTION

Embodiments of a simplified dental template are disclosed to supportpositioning an object on a patient's tooth oriented in such a way thatall objects as a whole are lined up to a user defined ideal arrangement.The template allows direct bonding of brackets and can be fabricatedaccording to a simplified process, which is also disclosed herein. Theprocess includes digitizing only some of the patient's teeth and/orsimplifying the anatomical features of at least some of the patient'steeth; adding virtual objects to predetermined locations on thedigitized teeth; and fabricating the dental template to locate theobject on the patient's teeth. The dental template is designed to locateeach object at a predetermined inclination or a predetermined angulationon the patient's tooth. The template can be used for etching or forpositioning brackets on teeth. The skilled artisan will understand thatthe elements of the template and/or concepts of the fabrication methodsdescribed herein can be mixed and matched. For example, a template maybe created using some steps from one method and other steps from one ormore other methods.

The template is formed of a polymeric shell having a cavity shaped tofit over a patient's teeth and has openings that allow standardizedbrackets to be accurately positioned on teeth regardless of toothsurface variations from the norm for which the bracket base designed.The treatment can be done virtually and the placement of the bracketscan be done using a template device that is a removable guide. Thisdevice allows precise placement of the bracket and enables bracketplacement onto specific teeth independent of overall arch geometry. Thetemplate makes it easier for a less well-trained or an untrained personto bond a bracket. The system minimizes variations in the perception ofdistance and angles. The template allows precise control of theplacement of the bracket. Since bracket placement is one of the criticalvariables to successful treatment, the template improves treatmentprecision from patient to patient and from tooth to tooth.

FIG. 1 shows an exemplary process of fabricating a dental template forpositioning an object on a patient's tooth. First, the process digitizesthe patient's tooth (10). Next, virtual objects are added topre-determined locations on the digitized tooth (12). Finally, theprocess fabricates the dental template to locate the object on thepatient's tooth (14). One detailed implementation of the method of FIG.1 is described with reference to FIGS. 3A-3E below.

FIG. 2A shows an exemplary process for placing an orthodontic object ona patient's tooth. The process uses the template fabricated in theprocess of FIG. 1. The process includes placing the template on thepatient's teeth (20); mounting the orthodontic object between thetemplate and the tooth (22); and bonding the orthodontic object to thetooth (24). In the bonding operation, chemical curing or light curingadhesives can be used. In chemical curing, separately supplied curingcomponents are mixed together and a small quantity of the mixture isplaced on the back of the bracket prior to placing the bracket on thetooth. Light-curable adhesives include a photo-initiator that initiatesthe curing reaction once the adhesive is exposed to a sufficient amountof light. A common method of using light-curable adhesives for directbonding includes the steps of placing a small quantity of the adhesiveon the base of the bracket and then placing the bracket on the patient'stooth. The practitioner then shifts the bracket on the tooth as may beneeded. Once the bracket is in its intended location, light from adental curing unit is directed toward the adhesive for a time periodsufficient to satisfactorily cure the adhesive.

FIG. 2B shows a second process of placing the orthodontic object on apatient's tooth. In this process, the orthodontic object is placed inthe template (30). Next, the process includes inserting the templatecontaining the orthodontic object onto the patient's teeth (32).Finally, the process includes bonding the orthodontic object to thetooth (34).

FIG. 3A illustrates an exemplary process for fabricating the dentaltemplate. First, a digital model of a patient's teeth is obtained (102).The digital model can be obtained in a variety of ways. For example, thepatient's teeth, or models thereof or impressions may be scanned orimaged using well-known technology, such as two or, three dimensionalX-rays, computer-aided tomographic images or data sets, magneticresonance images, etc. There are a variety of range acquisition systems,generally categorized by whether the process of acquisition requirescontact with the three dimensional object (e.g., tooth) to be imaged. Acontact-type range acquisition system uses a probe having multipledegrees of translational and/or rotational freedom. By recording thephysical displacement of the probe as it is drawn across the samplesurface of the object, a computer-readable representation of the sampleobject is made. A noncontact type range acquisition device can be eithera reflective-type or transmissive-type system. There are a variety ofreflective systems in use. Some of these reflective systems usenon-optical incident energy sources, such as microwave radar or sonar.Others use optical energy. The non-contact type systems working byreflected optical energy further contain special instrumentationconfigured to permit certain measuring techniques to be performed (e.g.,imaging radar, triangulation, and interferometry).

According to one embodiment, a digital model of only certain of thepatient's teeth is obtained. For example, at least three teeth aredigitized using one of the digitizing or scanning methods describedabove. According to an embodiment, four teeth are digitized for each ofthe upper (maxillary) and lower (mandibular) templates. In thisembodiment, the four teeth for each of the upper and lower templatesinclude the two central incisors and the two rearmost molars. Theskilled artisan will understand that these four teeth can providestability for positioning the template on a patient's teeth. In analternative embodiment, three teeth for each of the upper and lowertemplates can be digitized: one of the central incisors and twomirror-image molars. According to another embodiment, all of thepatient's teeth are digitized and a simplified digital model is latercreated, as discussed in more detail below.

Next, virtual brackets are selected and added (104) to the digital modelof the patient's teeth. The virtual brackets are three-dimensional (3D)virtual models of physical brackets. The 3D model may be a computeraided design (CAD) model or may be scanned using scanners, as describedabove. The virtual brackets may be positioned on a digitized tooth usinga computer or workstation having a suitable graphical user interface(GUI) and software appropriate for viewing and modifying the images. Theabove-described component identification and component manipulationsoftware is designed to operate at sophistication commensurate with theoperator's training level. For example, the component manipulationsoftware can assist a computer operator, lacking orthodontic training,by providing feedback regarding permissible and forbidden manipulationson the teeth. On the other hand, an orthodontist, having greater skillin intra-oral physiology and teeth-moving dynamics, can simply use thecomponent identification and manipulation software as a tool and disableor otherwise ignore the device.

While the methods described herein may rely on computer manipulation ofdigital data, the dental template or appliance may be produced bynon-computer-aided techniques. For example, plaster casts, obtained asdescribed above, may be cut using knives, saws, or other cutting toolsin order to permit repositioning of individual teeth within the casting.The disconnected teeth may then be held in place by soft wax or othermalleable material, and a plurality of intermediate tooth arrangementscan then be prepared using such a modified plaster casting of thepatient's teeth. The different arrangements can be used to prepare thetemplate using pressure and vacuum molding techniques. While such manualcreation of the appliance systems will generally be less preferred,appliance systems so produced will come within the scope of the presentinvention.

Using the CAD workstation, a combined digital model of the virtualbrackets and the teeth can be produced (106). In one implementation, oneof the two following template embodiments can be selected:Direct-Unified and Indirect-Unified, as discussed in more detail withreference to FIG. 3B.

Once the template has been fabricated, according to one embodiment, thetemplate is set over the model of the patient's dental arches orotherwise positions the template in the approximate locations of theirrespective teeth. A thermoformed cast, or otherwise formed layer offlexible material, is deposited on the bodies of the templates and makesrelatively durable contact with the bodies of the templates. This methodmay be performed either in a factory or in an orthodontist's office.

The system can produce both the template bodies and the inter-toothposition(s) at the same time and subsequently alters the stiffness ofthe various parts. One way of achieving this would be to produce theentire arch with a 3D printer, mask the tooth bodies from theinter-tooth portions, and invest the tooth bodies with a rigidifyingagent and the inter-tooth portions with an agent to create flexibility.

As shown in FIG. 3A, from 110, if a directly formed template isproduced, the process proceeds to 114, where each tooth is scaled; acavity is then formed to enclose the tooth when the dental template orappliance is inserted over the patient's teeth. Next, excess material orunnecessary structures (e.g., anatomies of certain teeth, occlusalportions, and gingival portions) are removed from the digital model. Thedigital model is produced as a physical model. A flexible, pliable layeris formed and the resulting combination is trimmed to allow proper fitand function.

From 108, if a template of a whole arch (not articulated) is to beproduced, the process proceeds to 116. In the case of anindirectly-produced template, the process forms an Aligner and excessmaterial is removed (118).

In the case of a directly formed whole arch template, the processproceeds from 116 to 120 where the entire arch is scaled; cavities arethen formed to enclose the arch when the dental template or appliance isinserted over the patient's teeth. Next, excess material or unnecessarystructures (e.g., certain teeth, occlusal portions, gingival portions)are removed from the digital model. The digital model is produced as aphysical model. A flexible, pliable layer is formed and the resultingcombination is trimmed to allow proper fit and function.

FIG. 3B shows a process for providing two possible templates. First, theprocess acquires a digital model of dentition, adds virtual brackets tothe teeth, and creates a combined model (180) including the dentitionand the virtual brackets. Next, one of two template options can beselected.

The first option is a unified (or single piece) direct fabricationoption where the process scales the patient's dental arch (about105-150%), locates the original arch and scaled arch in the same 3-Dspace, creates a cavity of the original inside the scaled arch, removesgingival portions, tooth geometries of the occlusal portions of mostteeth except for the positioning teeth, substantial portion of lingualtooth surfaces, substantial portion of the buccal surfaces, andbuccogingival surfaces covering virtual brackets, and produces a realarch model from the digital model (182). For example, the occlusalportions of most of the teeth (i.e., teeth that are not used aspositioning teeth) in the real arch model (and also the simplifiedcombined digital model) may be substantially planar. According to anembodiment, not only are the tooth geometry features significantlyreduced and simplified as noted above, but also the number of teethhaving features reproduced; for example, a great deal of the toothgeometries are removed from all teeth except for four or fewer teethused as positioning teeth. In one exemplary embodiment of a template 600illustrated in FIGS. 3C-3E, only certain features are reproduced forfour positioning teeth in each of the upper (maxillary) and lower(mandibular) templates: the two central incisors 610 (e.g., teeth #24and #25 in the lower template) and the two rearmost molars 620 (e.g.,teeth #19 and #30 in the lower template). For example, the occlusalsurfaces are reproduced only for these four teeth 610, 620; theremaining teeth have substantially planar occlusal surfaces because theyare simplified. The skilled artisan will appreciate that the four teeth610, 620 and their reproduced features are useful in positioning thetemplate 600 on the patient's dental arch, and that the simplified realarch model may be fabricated more quickly because it has fewerreproduced features of the patient's teeth. Such a simplified model andtemplate 600 made using such a simplified model also requires lessmaterial. According to the embodiment of FIGS. 3C-3E, the template 600is positioned using only the incisal surfaces of the central incisors610 and the occlusal surfaces of the rearmost molars 620, rather thanusing all teeth. As shown in FIGS. 3C-3E, the incisal and occlusalsurfaces are reproduced only in the central incisors 610 and rearmostmolars 620. As shown in FIG. 3C, the occlusal surfaces of the remainingteeth in the template 600 are substantially planar, as they have beensimplified and those of skill in the art will understand that adequateclearance in the upper and lower templates should be provided to limitocclusal surface contact for these other simplified teeth. It will beunderstood that the reproduced occlusal features of the central incisors610 and the rearmost molars 620 are used to locate the template 600along the z-axis and the template walls contacting each tooth's buccalsurface are used to locate and secure the template 600 in the x and ydirection. The skilled artisan will appreciate that only the occlusalsurfaces of the patient's teeth having reproduced occlusal features onthe template 600 contact the template 600 when the template ispositioned on the patient's teeth. In alternative embodiments, otherteeth can be selected for positioning the template. For example, for theupper template, teeth #2, #8, #9, and #15 may be selected and teeth 318,#24, #25, and #31 may be selected for the lower template. Also as notedabove, three teeth may be selected: preferably, one of the centralincisors and two contra lateral molars. The digital model is thenconverted to a physical model, likely through the use of a rapidprototyping method (e.g., Fused Deposition Modeling, 3-D Printing, andstereo lithography).

In the second option (unified indirect fabrication), the processproduces a real model (e.g., mold) of the arch from a simplified digitalmodel and forms a removable appliance (aligner) template on the realmodel of the arch. The real model can be fabricated using rapidprototyping methods. The skilled artisan will understand that thedigital model is simplified by removing occlusal portions and buccalportions such that they are substantially planar in most of the teeth.The template is removed from the real model, and the process continuesby removing gingival portions, substantial portion of lingual toothsurfaces, and buccogingival surfaces covering virtual brackets from thetemplate (184). According to an embodiment, not only are the toothgeometry features significantly reduced and simplified, as noted above,but also the number of teeth having features reproduced on the realmodel of the arch; for example, the entire tooth geometries are removedfrom all teeth except for four or fewer teeth. In one embodiment, onlycertain features of four teeth remain for each of the upper (maxillary)and lower (mandibular) templates: the two central incisors and the tworearmost molars. The skilled artisan will appreciate that, as discussedabove, these teeth and their reproduced features are useful inpositioning the template on the patient's dental arch, and that thesimplified real arch model may be fabricated more quickly because it hasfewer features of the patient's teeth. The digital model is thenconverted to a physical model, likely through the use of a rapidprototyping method (e.g., Fused Deposition Modeling, 3-D Printing, andstereolithography).

In one embodiment, the template 600 is made from a thicker material (forexample, at least 0.03 inch) to provide the user with more guidance inthe depth direction. The thicker material for the template 600 ispreferably in a range of about 0.02-0.06 inch, more preferably in arange of about 0.03-0.05 inch, and even more preferably about 0.04 inch.Furthermore, the thicker template allows easier positioning of thebracket to the tooth as there is more bracket surface area supported bythe material. The template 600 may be made from materials that containphysical property switches for ease of removal. These switches mightinclude temperature responsive, pH responsive, moisture responsive, or amulti-layer system wherein the layers have varying physical properties.More information on the fabrication of a dental template or appliance isdisclosed in U.S. patent application Ser. No. 10/794,324, entitled“Systems and Methods for Fabricating a Dental Template With a 3-D ObjectPlacement,” filed Mar. 4, 2004, the entire disclosure of which is herebyincorporated herein by reference.

Another embodiment of the template can be used for etching bondingchemicals on the patient's teeth. An etching template allows thepractitioner to precisely etch the areas of the teeth on which thebracket will be placed. The etching template directs the user topredetermined locations on the teeth surface that need to be bonded. Theetching template can be either a windowed template or a concave surfacedtemplate where bonding gel is loaded or pre-loaded into the concavity.In some embodiments, cut-outs or windows of the template bound theregions to be etched to minimize teeth sensitivity to etching orunwanted enamel removal. In another embodiment of the etching template,the cut-outs or windows are not formed; instead, those areas are formedas concavities facing the tooth surfaces. The concavities can contain anetching compound, which can be exposed or activated prior to setting thetemplate on the teeth.

Various alternatives, modifications, and equivalents may be used in lieuof the above components. Additionally, the techniques described hereinmay be implemented in hardware or software, or in a combination of thetwo. The techniques may be implemented in computer programs executing onprogrammable computers that each includes a processor, a storage mediumreadable by the processor (including volatile and nonvolatile memoryand/or storage elements), and suitable input and output devices. Eachprogram can be implemented in a high level procedural or object-orientedprogramming language to operate in conjunction with a computer system.However, the programs can be implemented in assembly or machinelanguage, if desired. The language may also be a compiled or interpretedlanguage. Each such computer program can be stored on a storage mediumor device (e.g., CD-ROM, hard disk, magnetic diskette) that is readableby a general or special purpose programmable computer for configuringand operating the computer when the storage medium or device is read bythe computer to perform the procedures described. The system also may beimplemented as a computer-readable storage medium, configured with acomputer program, where the storage medium causes a computer to operatein a specific and predefined manner. Further, while the invention hasbeen shown and described with reference to an embodiment thereof, thoseskilled in the art will understand that the above and other changes inform and detail may be made without departing from the spirit and scopeof the following claims.

What is claimed is:
 1. A system for positioning an object on teeth of apatient, the system comprising: one or more processors; and memory,including instructions executable by the one or more processors to causethe system to at least: receive a digital model of an arch of a patientcomprising a first subset of teeth and a second subset of teeth;generate a digital model of a polymeric shell shaped to fit over aportion of the arch of the teeth of the patient, the shell comprising afirst portion shaped to receive the first subset of the teeth of thearch and a second portion shaped to receive the second subset of theteeth of the arch, the first portion comprising one or more toothreceiving cavities having occlusal or incisal geometries correspondingto occlusal or incisal tooth geometries of the first subset of theteeth, and the second portion comprising a planar occlusion portionspanning the second subset of the teeth, the planar occlusion portionhaving a continuous planar geometry comprising a reduced number ofocclusal features relative to a number of occlusal features of thesecond subset of the teeth; determine whether the polymeric shell isarticulated or not articulated; remove structures from the digital modelof the polymeric shell based on the determination; and output the modelof the polymeric shell for direct or indirect fabrication based on thedetermination.
 2. The system of claim 1, wherein the first subset of theteeth includes no more than four of the teeth and the one or more toothreceiving cavities of the first portion of the shell have occlusalgeometries that correspond to occlusal surfaces of corresponding teethof the patient.
 3. The system of claim 2, wherein the no more than fourof the teeth comprise at least one central incisor and two mirror-imagemolars.
 4. The system of claim 1, further comprising a plurality ofbracket models positioned on the model of the arch of the patient. 5.The system of claim 1, wherein the model of the polymeric shell isconfigured to control placement of the object on the teeth of thepatient.
 6. The system of claim 1, wherein the shell further comprisesone or more openings shaped to control placement of one or more objectson the teeth of the patient.
 7. The system of claim 6, wherein the oneor more objects comprise at least one bracket.
 8. The system of claim 6,wherein the one or more openings are shaped to locate each of the one ormore objects at a predetermined inclination or predetermined angulationon the teeth of the patient.
 9. The system of claim 1, wherein the firstportion reproduces at least one occlusal feature of the first subset ofthe teeth.
 10. One or more non-transitory computer-readable storagemedia having stored thereon executable instructions that, when executedby one or more processors of a computer system for positioning an objecton teeth of a patient, cause the computer system to at least: receive adigital model of an arch of a patient comprising a first subset of teethand a second subset of teeth; generate a digital of a polymeric shellshaped to fit over a portion of the arch of the teeth of the patient,the shell comprising a first portion shaped to receive the first subsetof the teeth of the arch and a second portion shaped to receive thesecond subset of the teeth of the arch, the first portion comprising oneor more tooth receiving cavities having occlusal or incisal geometriescorresponding to occlusal or incisal tooth geometries of the firstsubset of the teeth, and the second portion comprising a planarocclusion portion spanning the second subset of the teeth, the planarocclusion portion having a continuous planar geometry comprising areduced number of occlusal features relative to a number of occlusalfeatures of the second subset of the teeth; determine whether thepolymeric shell is articulated or not articulated; remove structuresfrom the digital model of the polymeric shell based on thedetermination; and output the model of the polymeric shell for direct orindirect fabrication based on the determination.
 11. The one or morenon-transitory computer-readable storage media of claim 10, wherein thefirst subset of the teeth includes no more than four of the teeth andthe one or more tooth receiving cavities of the first portion of theshell have occlusal geometries that correspond to occlusal surfaces ofcorresponding teeth of the patient.
 12. The one or more non-transitorycomputer-readable storage media of claim 11, wherein the no more thanfour of the teeth comprise at least one central incisor and twomirror-image molars.
 13. The one or more non-transitorycomputer-readable storage media of claim 10, further comprising aplurality of bracket models positioned on the model of the arch of thepatient.
 14. The one or more non-transitory computer-readable storagemedia of claim 10, wherein the model of a polymeric shell is configuredto control placement of the object on the teeth of the patient.
 15. Theone or more non-transitory computer-readable storage media of claim 10,wherein the shell further comprises one or more openings shaped tocontrol placement of one or more objects on the teeth of the patient.16. The one or more non-transitory computer-readable storage media ofclaim 15, wherein the one or more objects comprise at least one bracket.17. The one or more non-transitory computer-readable storage media ofclaim 15, wherein the one or more openings are shaped to locate each ofthe one or more objects at a predetermined inclination or predeterminedangulation on the teeth of the patient.
 18. The one or morenon-transitory computer-readable storage media of claim 10, wherein thefirst portion reproduces at least one occlusal feature of the firstsubset of the teeth.